The focus of this project is three-fold: (1) to characterize uptake and intracellular processing of unmodified and modified oligonucleotides; (2) to utilize antisense and antigene technology in several in vitro model systems to identify critical events in cell proliferation/viral replication; and (3) to study the efficacy of antisense and antigene reagents as in vivo modulators of gene expression. (1) We have characterized the uptake of unmodified oligos as an enery- dependent, endocytic process, mediated by at least one cell surface- binding protein. We have devised a novel technique to study oligo uptake, intracellular localization, and association with protein and nucleic acids. This non-invasive technique will permit subcellular localization over time of an internalized oligo. (2) We have confirmed that c-myc inhibition is cytostatic for normal and malignant lymphoid cells and that some Burkitt lymphoma cells can be specifically growth-arrested in vitro with a novel c-myc antisense. We have confirmed that N-myc inhibition leads to reduction in growth secondary to alteration in differentiative status of neuroectoderm-derived cell lines. We have demonstrated that interruption of TGF and autocrine loops is cystostatic for epithelial and mesenchymal cells. (3) We have demonstrated that continuous subcutaneous perfusion of an oligo can significantly arrest in vivo its targeted gene expression and reproduces other in vitro phenomena observed with either DNA or RNA antisense. This model permits in vivo testing of antisense oligos for efficacy and toxicity. We have demonstrated the feasibility of continuous perfusion intrathecal model to study the clinical efficacy of antisense in a more relevant pre-clinical in vivo model system.